The invention relates to a traction roller transmission with fixed transmission ratio, particularly to a planetary-type traction roller transmission.
Such a transmission includes a traction ring having disposed therein a sun roller and planetary rollers which are arranged in the annular space between, and in engagement with, the sun roller and the traction ring for transmission of motion between the sun roller and the traction ring. As disclosed in the present inventor's eariler U.S. Pat. No. 3,776,051, the sun roller may be so arranged that its axis is parallel to, but spaced from, the axis of the traction ring such that the annular space between the sun roller and the traction ring is of varying width, the traction rollers being so arranged that at least one of them is driven by the reaction forces into a narrowing section of the annular space when a torque is transmitted. Alternatively, as disclosed in the inventor's U.S. Pat. No. 4,275,610 or in U.S. Pat. No. 3,610,060, other means such as expanding sun rollers or compressing traction rings may be provided to cause firm engagement of the traction rollers with the sun roller and the traction ring when a torque is transmitted through the transmission.
In any case, the traction rollers must be guided into parallel alignment with the traction ring and sun roller in order to keep wear and friction losses to a minimum. As a result, the traction rollers need to be supported with some amount of freedom so that they can move freely into proper positions for transmission of torque and for minimum wear and friction. Resilient supports for the rollers however are usually relatively complicated and expensive and, consequently, not suitable for small transmissions.
It is therefore the principal object of the present invention to provide a traction roller transmission having planetary-type traction rollers with a relatively inexpensive support structure that gives the traction rollers the necessary amount of freedom for proper positioning.
It is also an object to provide inexpensive guide means for guiding the traction roller axes into parallel alignment with the sun roller and traction ring axes as permitted by the freedom given to the traction rollers.